// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef DRACO_CORE_DATA_BUFFER_H_
#define DRACO_CORE_DATA_BUFFER_H_

#include <cstring>
#include <ostream>
#include <vector>

#include "draco/core/draco_types.h"

namespace draco {

// Buffer descriptor servers as a unique identifier of a buffer.
struct DataBufferDescriptor {
    DataBufferDescriptor() : buffer_id(0), buffer_update_count(0) {}
    // Id of the data buffer.
    int64_t buffer_id;
    // The number of times the buffer content was updated.
    int64_t buffer_update_count;
};

// Class used for storing raw buffer data.
class DataBuffer {
  public:
    DataBuffer();
    bool Update(const void *data, int64_t size);
    // TODO(zhafang): The two update functions should be combined. I will
    // leave for now in case it breaks any geometry compression tools.
    bool Update(const void *data, int64_t size, int64_t offset);

    // Reallocate the buffer storage to a new size keeping the data unchanged.
    void Resize(int64_t new_size);
    void WriteDataToStream(std::ostream &stream);
    // Reads data from the buffer. Potentially unsafe, called needs to ensure
    // the accessed memory is valid.
    void Read(int64_t byte_pos, void *out_data, size_t data_size) const {
        memcpy(out_data, data() + byte_pos, data_size);
    }

    // Writes data to the buffer. Unsafe, caller must ensure the accessed memory
    // is valid.
    void Write(int64_t byte_pos, const void *in_data, size_t data_size) {
        memcpy(const_cast<uint8_t *>(data()) + byte_pos, in_data, data_size);
    }

    // Copies data from another buffer to this buffer.
    void Copy(int64_t dst_offset, const DataBuffer *src_buf, int64_t src_offset,
              int64_t size) {
        memcpy(const_cast<uint8_t *>(data()) + dst_offset,
               src_buf->data() + src_offset, size);
    }

    void set_update_count(int64_t buffer_update_count) {
        descriptor_.buffer_update_count = buffer_update_count;
    }
    int64_t update_count() const {
        return descriptor_.buffer_update_count;
    }
    size_t data_size() const {
        return data_.size();
    }
    const uint8_t *data() const {
        return data_.data();
    }
    uint8_t *data() {
        return &data_[0];
    }
    int64_t buffer_id() const {
        return descriptor_.buffer_id;
    }
    void set_buffer_id(int64_t buffer_id) {
        descriptor_.buffer_id = buffer_id;
    }

  private:
    std::vector<uint8_t> data_;
    // Counter incremented by Update() calls.
    DataBufferDescriptor descriptor_;
};

}  // namespace draco

#endif  // DRACO_CORE_DATA_BUFFER_H_
